JP7073684B2 - Travel control device - Google Patents

Description

The present invention relates to a hybrid vehicle and a traveling control device thereof.

In hybrid vehicles, various driving controls aimed at optimization are performed in order to improve fuel efficiency as much as possible. In a hybrid vehicle that can run only by driving a motor with the power stored in the rechargeable battery, if there is a margin in the amount of charge (SOC), EV (Electric Vehicle) running as an electric vehicle without starting the engine at the time of starting Can be started with. The smooth driving feeling during EV driving driven by the motor leads to a comfortable drive. In particular, the motor is advantageous for accelerating the start, so it is desirable to give priority to EV driving as much as possible. If the SOC is slightly insufficient, the engine is started while assisting with the motor, and if the SOC is further insufficient, the engine is started only. That is, the start condition is switched according to the magnitude of the SOC. If there is a margin, EV driving is used, if the margin is small, assisted driving is used, and if there is no margin, engine driving is used.

The motor used for driving is also charged by regenerative energy and is controlled so as to recover SOC as appropriate. However, since it is useless to drive the engine even when the vehicle is stopped because the priority is given to charging, a hybrid vehicle in which the engine is stopped when the vehicle is stopped is proposed in Patent Document 1.

Japanese Unexamined Patent Publication No. 10-174208

However, when switching the traveling mode, it may not be sufficiently optimal if it is judged only by the SOC threshold value. Basically, the threshold is set to be optimal when trying to travel a long distance. However, even if the SOC is such that long-distance EV driving or assisted driving is unlikely to be possible, if you want to start over a little after parking, or if you want to back up a very short distance, you can do it at a very short distance. If so, it often leaves enough capacity for EV driving.

Therefore, an object of the present invention is to further reduce unnecessary engine starting and promote energy saving in driving control of a hybrid vehicle.

The present invention solves the above-mentioned problems.
When driving a hybrid vehicle, it is determined whether or not the vehicle is driven by a motor or driven by an engine with motor assist, depending on the battery charge status, and the driving mode can be switched between driving by engine only. It ’s a device,
A short-distance movement estimation means for determining whether or not a predetermined condition for presuming that the hybrid vehicle is a short-distance movement is executed at the start of traveling of the hybrid vehicle is executed.
If the above conditions are met
Even if the charging status is lower than the threshold value for determining that the vehicle is normally not driven by the motor, a traveling control device that enables the vehicle to be driven by the motor is adopted.

Here, one of the above conditions can be adopted such that the time from the stop of the previous ignition to the start of the new ignition is equal to or less than the predetermined short-distance movement determination time.

Further, one of the above conditions can adopt a configuration in which the shift position is reverse. Further, in this configuration, when a predetermined second condition is satisfied, even if the shift position is reverse, it is possible to adopt a configuration in which the motor-driven travel is switched to another travel mode. As the second condition, a configuration can be adopted in which the speed becomes equal to or higher than a predetermined threshold value, or the mileage becomes equal to or higher than a predetermined threshold value. It is possible to adopt a configuration in which the threshold value is set to a different value depending on the charging status.

Further, it is possible to adopt a configuration in which the vehicle is switched to the engine drive only when the battery charge status becomes equal to or less than the battery limit for determining that the motor drive is impossible after the control to drive the motor.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to suppress engine start under conditions that can be discriminated as short-distance travel, as compared with the case where uniform driving mode switching is performed only by the SOC threshold value in a hybrid vehicle, and overall operation is possible. Further energy saving can be realized in.

Conceptual diagram of a hybrid vehicle provided with an embodiment of a travel control device according to the present invention. Relationship diagram of threshold values in SOC determined by the travel control device A flowchart showing a control example of the travel control device according to the present invention.

The present invention relates to a travel control device 12 that controls a travel mode of a hybrid vehicle 11 having a motor 14 and an engine 15 as shown in FIG. The motor 14 can transmit rotation to one of the shafts 21 (or the shaft 22) of the hybrid vehicle 11, and can receive regenerative energy from the shaft 21 (or the shaft 22) to generate electricity. Although not shown, the hybrid vehicle 11 has a rechargeable battery, is charged by the motor 14, and drives the motor 14.

In this example, the situation where the shaft 21 rotates the front wheels 27 and the shaft 22 rotates the rear wheels 28 will be described. However, in the present invention, the relationship between the front wheels 27, the rear wheels 28, the motor 14, and the engine 15 may be reversed.

In addition to the motor 14, a motor 17 used for starting the engine 15 may be provided.

The hybrid vehicle 11 provided with the travel control device 12 according to the present invention is driven by a motor 14 (EV traveling), driven by an engine 15 (engine traveling), and driven by an engine 15 assisted by the motor 14 (engine +). It is possible to switch between three driving modes (motor driving). This traveling mode is basically switched according to the charging status (SOC: State of Charge) of the rechargeable battery of the hybrid vehicle 11. If there is a margin in the SOC, EV driving is possible, so there is no need to start the engine. If there is no room in the SOC, the motor alone cannot run, and the engine + motor running or the engine running, so it is necessary to start the engine.

The above SOC is set as shown in FIG. a is an EV travelability determination value, and if the SOC is a or more, EV travel is performed. This is not a value that the motor 14 can be started by itself, but a value that indicates that the motor 14 alone has a sufficient amount of electric power to be able to travel a certain distance. b is a motor drive assist enable determination value, and if the SOC is b or more and less than a, the engine + motor running assisted by the motor 14 is performed. If the motor 14 is to be operated by itself, the amount of electric power is exhausted at an early stage, but it is a value indicating that the amount of electric power is sufficiently sufficient to be used as an assist. If the SOC is less than b, the engine is basically run. Naturally, a> b.

However, the travel control device 12 according to the present invention sets a battery limit determination value c, which is a value lower than b. That is, a> b> c. This value c is a limit value at which the hybrid vehicle 11 can be operated with only the motor 14 without starting the engine 15 within a short distance. The travel control device 12 according to the present invention causes EV travel under the conditions described later even in a situation where the SOC is c or more and less than b, or c or more and less than a.

An example of distribution when the travel control device 12 according to the present invention controls the engine 15, the motor 14, the first clutch 24 connected to the engine 15, and the second clutch 25 connected to the motor 14 will be described. First, Table 1 shows the situation when SOC ≧ a. The column title is the shift position, P is parking, R is reverse, N is neutral, and D is drive. The engine 15 does not start, and the first clutch 24 connected to the engine 15 remains open. When the shift position is R or D, the motor 14 is driven, the second clutch 25 is closed, and the shaft 22 is rotated.

Next, Table 2 shows the situation when SOC <c. Since the remaining battery power is low, the motor 14 is not driven at any shift position, and the second clutch 25 is left open. From the ready state, when the shift position is R or D, the engine 15 is driven, the first clutch 24 is closed, and the shaft 21 is rotated.

Further, Table 3 shows the situation when b ≦ SOC <a. Although the engine 15 is driven, the motor 14 is also driven and driven by the engine together with the assist by the motor 14. However, as will be described later, under the limited conditions when the shift position is R, the engine 15 may not be driven and the first clutch 24 may be opened.

As an exceptional process of the control as described above, the travel control device 12 according to the present invention determines whether or not a predetermined condition for presuming that the hybrid vehicle 11 is traveling a short distance is satisfied at the time when the hybrid vehicle 11 starts traveling. If the short-distance movement estimation means for determination is executed and the above conditions are satisfied, even if the SOC has a value that prohibits engine drive with motor assist (that is, below the value b), it is possible to drive by motor drive. It is controlled to be. Here, when there are a plurality of predetermined conditions, it may be estimated that the movement is a short distance if any one of the conditions is satisfied. However, the individual conditions that are selectively applied may be complex. As a result, if the vehicle travels a short distance, such as when parking is redone, the vehicle can be driven by the motor 14 as much as possible without starting the engine to save energy.

As a predetermined condition of the short-distance movement estimation means, for example, it is determined whether or not the time from the stop of the previous ignition to the start of a new ignition is equal to or less than the predetermined short-distance movement determination time α. Can be done. When re-parking, it is often the case that the ignition is stopped once, then the actual parking situation is confirmed, the vehicle is moved again immediately, and the vehicle is stopped again after a short distance. From this, it can be determined that if the period from the stop of the ignition to the start of the next ignition is short, it is highly possible that the parking is restarted. The specific α time depends on the driver's experience and vehicle type, but it is usually about 30 seconds to 1 minute. If the value of α is too large, there is a risk of erroneously recognizing a case where a long-distance move is performed after that, such as shopping after stopping for a short time instead of re-parking.

As another condition of the short-distance movement estimation means, for example, it can be determined whether or not the shift position is reverse. Basically, it is rare to travel a long distance in reverse, and in many cases it is sufficient to travel a short distance.

However, even if the shift position is reverse, it may move an exceptionally long distance. Therefore, it is preferable to set a predetermined second condition, and when the second condition is satisfied, control the motor-driven travel to another travel mode even if the shift position is reverse. The second condition includes, for example, when the speed v becomes equal to or higher than a predetermined threshold value, or when the mileage becomes equal to or higher than a predetermined threshold value. The speed v, which is the second condition, may be set in the range of 10 km / h to 40 km / h. Further, the speed condition to be set may be changed according to the SOC.

In addition, as a second condition for determining that the vehicle is moving a long distance exceptionally even if the shift position is reverse, a threshold value is set for the mileage instead of the speed, and if this threshold value is exceeded, it is determined that the vehicle is moving a long distance. You may try to do it. This threshold value may be adjusted as appropriate, and the conditions may be changed according to the SOC.

Further, as another condition of the short-distance movement estimation means, it is determined whether or not the distance to the destination input to the navigation device of the hybrid vehicle 11 is equal to or less than the threshold value for determining the short distance separately. May be good. Further, the same determination may be made by inputting the destination from the driver's smartphone or the like via the communication interface included in the travel control device 12 as well as the navigation device included in the hybrid vehicle 11.

Furthermore, as another condition of the short-distance movement estimation means, an interface such as a switch capable of directly transmitting the intention to the travel control device 12 when the driver is short-distance movement is provided, and the switch is turned on. If it becomes, it may be judged that the distance is short.

The travel control device 12 according to the present invention has a battery limit at which the SOC determines that the motor drive is impossible after the control for traveling by the motor drive (EV travel) once, regardless of the determination. When the value is c or less, it is advisable to switch to engine drive. The value c is a limit value that can be driven by the motor, and if it is less than that, there is a possibility that a problem may occur in the operation of other parts of the hybrid vehicle 11.

An example of a flowchart of control by the traveling control device 12 that combines the above-mentioned principle processing and exceptional processing will be described with reference to FIG. However, this is an example, and the present invention is not limited to this flowchart.

First (S101), when the ignition is turned off (S102), the travel control device 12 starts timer counting from the time when the ignition is turned off (S103). The count X (sec) is updated and continuously recorded in the storage device of the travel control device 12. When the ignition is turned on (S104), the timer count is stopped at that point (S105). However, only by stopping the update of the count, X (sec) at that time is retained in the storage device.

At this stage when the ignition is turned on, the travel control device 12 acquires the SOC value. If the SOC is less than c (S106 → NO), EV traveling by the motor 14 is not possible in any case, so the engine 15 is started and the engine is driven (S107). After running (S108), the process returns to the first judgment (S101). When the ignition is turned off again (S102), X (sec) is reset and counting starts from 0 (S103). Alternatively, X (sec) may be reset when the engine running is started.

Next, when the SOC is c or more in S106 (S106 → YES), the short-distance movement estimation means, which is an original determination by the traveling control device 12 according to the present invention, is executed. As the first step, it is determined whether or not the X (sec) held in the storage device is equal to or less than the preset short-distance movement determination time α (S111). If X ≦ α (S111 → YES), the travel control device 12 controls the clutch and the motor 14 so that the motor 14 performs EV travel without starting the engine 15 regardless of the shift position (S112). It is presumed that this is a re-stop after parking once.

However, this estimation may be incorrect. For example, if the travel distance from the start of travel is equal to or greater than the normal operation determination distance d (S113 → YES), which is predetermined as a criterion for determining normal operation, it is determined that the vehicle is long-distance travel. When such a determination can be made, the travel control device 12 switches to engine travel (S107). This normal driving determination distance d also depends on the driver's history and vehicle type, but if it exceeds 30 to 50 meters, for example, it may be judged that the normal driving is normal driving in many cases.

Further, even before the mileage becomes d or more (S113 → No), if the SOC becomes less than c (S114 → NO), the motor 14 cannot continue running, and the engine running is switched to (S113 → No). S107). EV driving is continued until any of these conditions is satisfied (S115 → S116 → NO). When it is determined that the running is completed within the range of the conditions under which the EV running can be continued (S116 → YES), the process returns to the first judgment in the same manner as above (S101). It should be noted that the end of traveling in S116 may be conditional on the ignition being turned off rather than the hybrid vehicle 11 being stopped.

Next, as the second step of the above-mentioned short-distance movement estimation means, when the timer count X exceeds the short-distance movement determination time (S111 → NO), that is, the time from the previous run has sufficiently elapsed. Make a judgment if there is. Here, it is determined whether or not the shift position is R (S121). If it is R (S121 → YES), there is a high possibility of short-distance movement. Here, the travel control device 12 determines whether the SOC is a or more (S122). If it is a or more (S122 → YES), even if it is a long-distance movement, EV running can be performed without any problem, so EV running is performed (S123).

Next, even when the SOC is less than a (S122 → NO), since the shift position is R, it can be determined that the vehicle is moving a short distance, and EV driving is performed as much as possible within the range where the SOC has a margin. As an example of this judgment, a judgment based on the vehicle speed v is shown. If the SOC is b or more (S124 → YES), there is some margin in the amount of electricity, so EV driving is initially performed as it is (S125 → NO → S123). Further, even if the SOC is less than b, it is (S124 → NO) c or more, so that EV driving is performed as it is at the beginning (S126 → NO → S123). However, when the SOC becomes less than c (S127 → NO), the engine is switched to running (S129). If you continue to drive (S128 → NO) and the vehicle speed exceeds 30km / h (S124 → YES → S125 → YES) when the SOC is b or more and less than a, it is a full-scale long-distance movement while reversing. Judgment is made and the engine is switched to running (S129). It should be noted that the engine may be switched to the engine + motor running with the assistance of the motor instead of the engine running. On the other hand, if the vehicle speed exceeds 15 km / h when the SOC is less than b (S124 → NO → S126 → YES), the SOC is judged to be a long-distance move as soon as possible because there is not enough room, and the engine is switched to running (S129). ). This difference in the set vehicle speed is adapted to the situation because the margin to the limit differs depending on the SOC. The value of each vehicle speed may be changed as appropriate depending on the driver's history, vehicle type, etc., and only an example is given here.

Although the judgment is made here based on the vehicle speed v, the judgment may be made based on the mileage instead of the vehicle speed v. In this case as well, it is preferable to set different values that serve as criteria for determining the mileage for switching to engine running depending on whether the SOC is greater than or equal to b and less than a and less than b, because more flexible response can be achieved. These values may be common to or different from the above-mentioned normal operation determination distance d.

When the travel control device 12 does not correspond to either stage of the short-distance travel estimation means (S121 → NO), the travel control device 12 simply switches the travel mode according to the SOC. However, when the shift position is P or N instead of D (S131 → NO), it waits for the determination when entering R as a standby state (S121). When the shift position becomes D (S131 → YES), the following judgment is made. If the SOC is a or more, EV running is performed (S132 → YES → S133). If the SOC is b or more and less than a (S132 → NO → S134 → YES), the vehicle is driven by the engine 15 assisted by the motor 14 (S135). If the SOC is less than b (S134 → NO), the engine 15 is used for traveling (S136). After S133 and S135, the SOC may be continuously determined (S132, S134).

Further, as a further application form of the control of this flowchart, another condition for presuming short-distance movement is inserted so that EV traveling is presumed to be short-distance movement even if the SOC is in the range of c or more and less than a. You may do it. Examples of the place where the additional condition is inserted include between S131 and S132.

11 Hybrid vehicle 12 Travel control device 14 Motor (directly connected to the shaft)
15 engine 17 motor (engine start)
21 Shaft (for front wheels)
22 Shaft (for rear wheels)
24 First clutch (of shaft 21)
25 Second clutch (of shaft 22)
27 Front wheels 28 Rear wheels a EV travelability judgment value b Motor drive assist possible judgment value c Battery limit judgment value d Normal operation judgment distance α Short-distance movement judgment time

Claims (6)

When driving a hybrid vehicle, it is determined whether or not the vehicle is driven by a motor and driven by an engine with motor assist, depending on the charging status of the rechargeable battery. It is a control device that can switch the driving mode with
A short-distance movement estimation means for determining whether or not a predetermined condition for presuming that the hybrid vehicle is a short-distance movement is executed at the start of traveling of the hybrid vehicle is executed.
If the above conditions are met
Even if the charging status is lower than the threshold value for determining not to drive by motor drive, it is possible to drive by motor drive .
One of the above conditions is a traveling control device in which the time from the stop of the previous ignition to the start of a new ignition is a predetermined time or less. The travel control device according to claim 1 , wherein one of the above conditions is a reverse shift position. The traveling control device according to claim 2 , wherein when a predetermined second condition is satisfied, even if the shift position is reverse, the traveling by the motor drive is switched to another traveling mode. The traveling control device according to claim 3 , wherein the second condition is when the speed becomes equal to or higher than a predetermined threshold value or when the traveling distance becomes equal to or higher than a predetermined threshold value. The traveling control device according to claim 4 , wherein a different value is applied as a threshold value in the second condition depending on the charging status. Claims 1 to 1 to switch to running by engine driving without motor driving when the charging status of the battery becomes equal to or less than the battery limit for determining that motor driving is impossible after the control of running by motor driving. 5. The traveling control device according to any one of 5.

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